1. Field of the Invention
This invention relates generally to automatic washers and means for dispensing liquid inside automatic washers at designated points during their programmed cycles of operation. More particularly still, the invention relates to means for dispensing liquid wash additives, e.g., fabric softeners or blueing, in automatic washers particularly those of the type which utilize intermittent or progressively staged acceleration of the agitator during spin cycles, and especially to dispensing means for such applications which provide for automatic dispensing operation at a desired point following the attainment of a predetermined spin velocity for a predetermined time over a course of both acceleration and deceleration.
2. Prior Developments and Previous Practices
A number of different types of dispensers for liquids in automated washing devices have been used heretofore, among which are such differing approaches as electromechanical devices which require programmed remote actuation, as well as a number of what are essentially self-actuated devices of a primarily mechanical nature which respond to various conditions during the operation of the washing machine, often a predetermined agitator speed threshold, to dispense liquids at some given point during the washing process without the need for external control devices.
Centrifugally actuated dispensers are frequently encountered in the latter group, and a good example of such a device is that shown in U.S. Pat. No. 4,656,844, which is commonly owned herewith and which is hereby incorporated by reference. As discussed in that patent, centrifugal dispensers typically employ a cup-like or other such receptacle which is usually either mounted upon the agitator or secured to the basket of the washing machine, such that liquid additive contained within the receptacle is forced upward and outward along the receptacle walls as the rotational speed of the agitator or basket increases, typically during a spin cycle, until the point is reached where the additive escapes over the edge of the receptacle. When the basket slows down, the fluid works its way to the wash basket to contact the wash load.
Various other forms of centrifugal liquid dispensers have also been proposed, as have various other types of devices based upon other and different physical principles, e.g., siphons, etc. Often, such other types of liquid dispensers are also related to or dependent upon agitator spin speed, as is true for example of the devices shown in U.S. Pat. Nos. 3,057,181 and 4,154,069, the first of which utilizes centrifugal force produced by the spinning agitator to load o prime the siphon tube while the latter uses an impact tube coupled to the agitator so that motion of the latter moves the impact tube through the liquid additive to be dispensed and causes the liquid to enter the impact tube and then move onward into the siphon. Many other particular approaches have been proposed, including the use of float-actuated dispensers, such as that shown in U.S. Pat. No. 3,724,242.
In order to achieve delayed dispensing at some later point during the washer operation, some dispensers have been proposed which utilize a pair or more of ganged or cascaded release stages. Thus, for example, U.S. Pat. No. 3,620,054 discloses a two-part centrifugal liquid dispenser which includes an inner-cup portion as well as an outer-cup or other such housing. Another different such type of device is shown in U.S. Pat. No. 4,691,538, which shows a staged pair of centrifugal dispenser sections disposed one above the other along the agitator axis. Somewhat similarly, the aforementioned U.S. Pat. No. 3,724,242 includes, with the float-actuated dispenser section already noted, a first centrifugally-operated dispenser section which discharges into the float-actuated dispenser section. To some extent, the aforementioned U.S. Pat. No. 4,154,069 might be considered a two-stage device, since the described impact tube structure which in effect loads the siphon could perhaps be considered a first stage and the siphon considered a second stage; indeed, this patent refers to the impact tube stage stage as a "timing means".
Notwithstanding the relatively extensive prior development of liquid-dispensing apparatus for automated washing machines, the continuing development of new and improved such machines brings about new circumstances and conditions which prior developments do not address and for which they do not provide solutions. In addition, continuing refinement of washer operation and sequences, together with advances and changes in detergents and additives, including for example fabric softeners, result in the apprehension of new and/or changed perceptions of the optimum time and conditions for dispensing wash additives.
Accordingly, many present-day automatic washers utilize selected and varying, non-constant agitator spin speeds, including "sub-interval" spin cycles. Furthermore, many such present-day washers utilize pulse actuation (energization) of the agitator drive motor. For example, reference is made to commonly-owned U.S. Pat. No. 4,779,431, which discloses and depicts particular details and aspects of such actuation, in accordance with which the agitator drive motor is energized by a series of electrical pulses whose duration and/or repetition rate is selected to gradually bring the agitator up to a desired spin speed over a period of time. With this type of actuation, the agitator actually undergoes an alternating sequence of positive and negative acceleration (i.e., deceleration), such that the resultant velocity profile comprises an alternating sequence along an increasing slope until the desired ultimate speed level is finally reached. As will be readily understood upon contemplation, such a velocity profile has an immediate and profound effect on centrifugally-actuated additive release mechanisms and may well result in their malfunction.
Accordingly, the need exists for a liquid additive dispenser for automatic washers which is readily adapted to washers with non-constant spin speeds and which, in addition, are preferably of a primarily or exclusively mechanical nature, which are self-actuating, and which have no moving parts which may produce undesired performance variations as well as malfunction and, ultimately, early failure. Furthermore, a need exists for a liquid wash additive dispenser which will operate to dispense the additive at a specific time near the end of the wash cycle, following certain increases and decreases in agitator speed, such that an optimum quantity of the additive (e.g., fabric softener) will remain in the wash load for optimal benefit during the subsequent drying cycle.